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A programming language for fun

Home Page: https://tjysdsg.github.io/tan/

License: MIT License

CMake 5.65% Shell 0.26% C 0.39% C++ 93.28% Dockerfile 0.42%

compiler programming-language llvm cpp tanlang tan language cmake cpp20

tan's Introduction

Jiyang (Mark) Tang

https://tjysdsg.github.io

I am a Software Engineer at Intel Corporation.

I obtained Master of Science in Intelligent Information Systems at Carnegie Mellon University Language Technologies Institute. I was fortunate to be advised by Dr. Shinji Watanabe. Under his supervision, I worked on speech processing problems and contributed to ESPnet

Before that, I obtained my joint Bachelor of Science in Data Science degree at Duke Kunshan University and Duke University.

tan's People

Contributors

Stargazers

Watchers

Forkers

dmitrykolesnikovich gmh5225

tan's Issues

Better error handling and error messages

Error handling shouldn't be done using C++ exceptions
Sometimes error messages are unclear, and the location of errors in source files is not intuitively formated

Package start_index and end_index into a class, and make it a required argument in Create()

Test struct.tan fails

tanc --print-ast --print-ir -I/mnt/d/repos/tan src/test/test_src/struct.tan -lruntime -L/mnt/d/repos/tan/runtime -o a.out 
[ERROR] at src/test/test_src/struct.tan:27 Cannot perform implicit type conversion
s.pfuck = &f; // pointer
        ^
0x7faa5edc39de: (__tan_assert_fail()+0xd)
0x7faa5edc4276: (tanlang::report_error(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, tanlang::Token*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)+0x3f7)
0x7faa5ee44004: (tanlang::AnalyzerImpl::report_error(tanlang::ASTBase*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)+0x44)
0x7faa5ee44f1b: (tanlang::AnalyzerImpl::analyze_assignment(tanlang::Assignment*)+0x23f)
0x7faa5ee43d12: (tanlang::AnalyzerImpl::analyze(tanlang::ASTBase*)+0xc2)
0x7faa5ee449ec: (tanlang::AnalyzerImpl::analyze_stmt(tanlang::ASTBase*)+0xa0)
0x7faa5ee43cef: (tanlang::AnalyzerImpl::analyze(tanlang::ASTBase*)+0x9f)
0x7faa5ee45602: (tanlang::AnalyzerImpl::analyze_func_decl(tanlang::ASTBase*)+0x13a)
0x7faa5ee43ec0: (tanlang::AnalyzerImpl::analyze(tanlang::ASTBase*)+0x270)
0x7faa5ee449ec: (tanlang::AnalyzerImpl::analyze_stmt(tanlang::ASTBase*)+0xa0)
0x7faa5ee43cef: (tanlang::AnalyzerImpl::analyze(tanlang::ASTBase*)+0x9f)
0x7faa5ee449ec: (tanlang::AnalyzerImpl::analyze_stmt(tanlang::ASTBase*)+0xa0)
0x7faa5ee43cef: (tanlang::AnalyzerImpl::analyze(tanlang::ASTBase*)+0x9f)
0x7faa5ee4370c: (tanlang::Analyzer::analyze(tanlang::ASTBase*)+0x2a)
0x7faa5edc5b31: (tanlang::Compiler::parse()+0x153)
0x7faa5edb4dab: (compile_files(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, TanCompilation*)+0x47f)
0x7faa5ed980e4: (cli_main(int, char**)+0x1335)
0x7faa5ed94360: (TanCTests::TestBody()+0x1e8)
0x7faa5eea419c: (void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)+0x69)
0x7faa5ee9cdad: (void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*)+0x5e)
0x7faa5ee767ec: (testing::Test::Run()+0xf2)
0x7faa5ee771f7: (testing::TestInfo::Run()+0x113)
0x7faa5ee77adc: (testing::TestSuite::Run()+0x12e)
0x7faa5ee84332: (testing::internal::UnitTestImpl::RunAllTests()+0x41c)
0x7faa5eea56b8: (bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)+0x69)
0x7faa5ee9df71: (bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*)+0x5e)
0x7faa5ee82a86: (testing::UnitTest::Run()+0xc4)
0x7faa5ed9407c: (RUN_ALL_TESTS()+0x15)
0x7faa5ed939bf: (main+0xb0)
0x7faa59c270b3: (__libc_start_main+0xf3)
0x7faa5ed936be: (_start+0x2e)

Process finished with exit code 134

Fuzzing findings

The following code crashes the compiler:

import""runtime/print.tan";
import "runtime/debug.tan";
import "runtime/math.tan";

fn close(a: float, b: float) : bool {
    return fabs(a - b) < 0.000001;
}

pub fn main(argc: int, argv: char**) : int {
    assert(1 * 2 == 2);
    assert(1.5 * 2 == 3.0);
    assert(1 + 1 == 2);
    assert(1.5 + 1.5 == 3.0);
    assert(3.926 * 2 == 3.1415926 * 2);
    assert(3.1415926 * 2 == 6.2831852);
    assert(0 - 1 == -1);
    assert(1 - 1 == 0);
    assert(5.2 - 0.3 != 4.9); // expect f32 precision problem
    assert(5.2 - 0.4 != 4.8); // expect f32 precision problem
    assert(close(5.2 - 0.3, 4.9));
    assert(close(5.2 - 0.4, 4.8));
    assert(13 / 3 == 4);
    assert(1.0 / 2.0 == 0.5);
    assert(55 / 11 == 5);
    assert(-55 / 11 == -5);
    assert(55.0 / 11.0 == 5.0);
    assert(-55.0 / 11.0 == -5.0);
    assert(55.0 / 11.0 == 5.0);
    assert(-55.0 / 11.0 == -5.0);
    assert(13 % 2 == 1);
    assert(5 % 3 == 2);
    assert(7 % 1 == 0);
    assert(close(5.3 % 2, 1.3));
    assert(13.5 % 2 == 1.5);
    print("SUCCESS\n");
    return 0;
}

call parser to parse files

tan/src/cli/tanc.cpp

Lines 30 to 33 in 12ad011

 // TODO: call parser to parse files 

 } 

 } 

 return 0;

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

Document type casts

check line breaks inside two quotation marks

tan/src/lexer/lexer.cpp

Lines 136 to 141 in 12ad011

 // TODO: check line breaks inside two quotation marks 

 token *tokenize_char(Reader *reader, code_ptr &start) { 

 token *t = nullptr; 

 auto forward = reader->forward_ptr(start); 

 const auto end = reader->back_ptr(); 

 forward = skip_until(reader, forward, '\'');

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

support escape sequences inside string literals

tan/src/lexer/lexer.cpp

Lines 155 to 160 in 12ad011

 // TODO: support escape sequences inside string literals 

 // TODO: check line breaks inside two quotation marks 

 token *tokenize_string(Reader *reader, code_ptr &start) { 

 token *t = nullptr; 

 auto forward = reader->forward_ptr(start); 

 forward = skip_until(reader, forward, '"');

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

Rename ASTBase::_lbp to _bp

The _bp of a NUD node is the right binding power, while the one of a LED is the left binding power

Test pointers.tan fails

/mnt/d/repos/tan/bin/tanc src/test/test_src/pointers.tan -Lruntime -lruntime -I. --print-ir
terminate called after throwing an instance of 'std::out_of_range'
  what():  _Map_base::at

Process finished with exit code 134

Implement enum

Enum declaration:

enum enum_name {
    e1 = 0,
    e2,
    e3 =255,
}

Allows specifying underlying data type (integers). Default to i32 if not specified.

enum E: i32 {
    e1,
    e2,
    e3,
}

Enums values are specified using dot (.):

var eee = E.e1;

Get enum name using @enum2str intrinsic:

var myenum = E.e1;
print(@enum2str(myenum)); // output "e1"

Enums can be implicitly casted to integers (but the some implicit conversion might be invalid depending their underlying type), but integers cannot be implicitly casted to enums.

More details in the example:

enum E: i16 {
    e1 = 0,
    e2,
    e3,
}
var i0: int = E.e1; // good
var i8:  = E.e1; // compile error, because i16 cannot be implicitly casted to i8
var e0: E = 0; // compile error
var e1: E = 0 as E; // good
var e2: E = -1 as E; // compile error, because E starts at 0

Enums cannot be implicitly casted from/to any types except integers and bools

Make string mutable

Code like this doesn't work:

pub fn main() : int {
    var s = "string";
    s[0] = 'p';
    assert(s[0] == 'p');
    return 0;
}

Error when compiling runtime without stack_trace.cpp

When compiling the runtime without strack_trace.cpp, LLVM reported the following error:

/mnt/d/repos/tan/bin/tanc -I. --shared -lunwind -o libruntime.so debug.tan stdlib.tan math.tan --print-ir
; ModuleID = 'debug.tan'
source_filename = "debug.tan"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

; Function Attrs: nounwind readnone willreturn
declare void @llvm.donothing() #0

declare extern_weak void @abort()

declare extern_weak void @stack_trace()

define void @assert(i1 %_b) !dbg !4 {
func_entry:
  %b = alloca i1
  call void @llvm.dbg.declare(metadata i1* %b, metadata !10, metadata !DIExpression()), !dbg !11
  store i1 %_b, i1* %b, !dbg !12
  call void @llvm.dbg.declare(metadata i1* %b, metadata !13, metadata !DIExpression()), !dbg !14
  %0 = load i1, i1* %b, !dbg !15
  %1 = icmp eq i1 %0, false, !dbg !15
  br i1 %1, label %then, label %fi, !dbg !15

then:                                             ; preds = %func_entry
  call void @abort(), !dbg !16
  br label %fi, !dbg !16

fi:                                               ; preds = %then, %func_entry
}

; Function Attrs: nounwind readnone speculatable willreturn
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1

attributes #0 = { nounwind readnone willreturn }
attributes #1 = { nounwind readnone speculatable willreturn }

!llvm.module.flags = !{!0, !1}
!llvm.dbg.cu = !{!2}

!0 = !{i32 2, !"Dwarf Version", i32 4}
!1 = !{i32 2, !"Debug Info Version", i32 3}
!2 = distinct !DICompileUnit(language: DW_LANG_C, file: !3, producer: "tan compiler", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
!3 = !DIFile(filename: "debug.tan", directory: ".")
!4 = distinct !DISubprogram(name: "assert", linkageName: "assert", scope: !3, file: !3, line: 3, type: !5, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !2, retainedNodes: !9)
!5 = !DISubroutineType(types: !6)
!6 = !{!7, !8}
!7 = !DIBasicType(name: "void", encoding: DW_ATE_signed)
!8 = !DIBasicType(name: "bool", size: 1, encoding: DW_ATE_boolean)
!9 = <temporary!> !{}
!10 = !DILocalVariable(name: "b", scope: !4, file: !3, line: 3, type: !8)
!11 = !DILocation(line: 3, column: 15, scope: !4)
!12 = !DILocation(line: 4, column: 16, scope: !4)
!13 = !DILocalVariable(name: "b", arg: 1, scope: !4, file: !3, line: 3, type: !8)
!14 = !DILocation(line: 3, column: 1, scope: !4)
!15 = !DILocation(line: 5, column: 6, scope: !4)
!16 = !DILocation(line: 6, column: 2, scope: !4)
Compiling TAN file: debug.tan.o
Basic Block in function 'assert' does not have terminator!
label %fi
in function assert
LLVM ERROR: Broken function found, compilation aborted!

But compiling the runtime with strack_trace.cpp was successful.

assert looks like this:

pub fn assert(b: bool) : void {
    if(!b) {
        @stack_trace();
        abort();
    }
}

LLVM added a cleanupret instruction after the abort call for some unknown reason (it didn't do this for other functions). Then tanc recognized that the function had a terminal instruction at the end of the body during IR generation, so no ret void instruction was inserted.

However, without including stack_trace.cpp, LLVM somehow removed the cleanupret instruction during binary code generation, thus reported the error above.

Update:
when compiling with stack-trace.cpp, the last instruction of the function body becomes opcode 104 (getOpcodeName() returns "<Invalid operator>")

Setup fuzzing

Use fuzzing to test the compiler

The compiler main function should only return 0 (successful compilation) or 1 (errors found in source code). By feeding random data to the compiler, we should find and fix bugs that causes it to crash, throw, or return unexpected value.

Move test directory out of src/

check file attributes before reading

tan/src/reader/reader.cpp

Lines 19 to 24 in 12ad011

 // TODO: check file attributes before reading 

 _filename = filename; 

 std::ifstream ifs(filename); 

 // read the whole file at once 

 std::string content((std::istreambuf_iterator<char>(ifs)), (std::istreambuf_iterator<char>())); 

 // count the number of lines

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

Test intrinsics.tan fails

/mnt/d/repos/tan/bin/tanc src/test/test_src/intrinsics.tan -Lruntime -lruntime -I. --print-ir
[ERROR] at src/test/test_src/intrinsics.tan:6 Invalid call to compprint, one argument with type 'str' required
@compprint("main function starts");
^
0x7fa6c4f5d5d8: (__tan_assert_fail()+0xd)
0x7fa6c4f5de70: (tanlang::report_error(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, tanlang::Token*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)+0x3f7)
0x7fa6c4ff9830: (tanlang::AnalyzerImpl::report_error(std::shared_ptr<tanlang::ParsableASTNode> const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)+0x4c)
0x7fa6c50194d2: (tanlang::AnalyzerImpl::analyze_intrinsic(std::shared_ptr<tanlang::ParsableASTNode> const&)+0x522)
0x7fa6c4ff8fff: (tanlang::AnalyzerImpl::analyze(std::shared_ptr<tanlang::ParsableASTNode> const&)+0xdf3)
0x7fa6c4ff83f7: (tanlang::AnalyzerImpl::analyze(std::shared_ptr<tanlang::ParsableASTNode> const&)+0x1eb)
0x7fa6c5015c41: (tanlang::AnalyzerImpl::analyze_func_decl(std::shared_ptr<tanlang::ParsableASTNode> const&)+0x265)
0x7fa6c4ff917a: (tanlang::AnalyzerImpl::analyze(std::shared_ptr<tanlang::ParsableASTNode> const&)+0xf6e)
0x7fa6c4ff83f7: (tanlang::AnalyzerImpl::analyze(std::shared_ptr<tanlang::ParsableASTNode> const&)+0x1eb)
0x7fa6c4ff83f7: (tanlang::AnalyzerImpl::analyze(std::shared_ptr<tanlang::ParsableASTNode> const&)+0x1eb)
0x7fa6c4ff7458: (tanlang::Analyzer::analyze(std::shared_ptr<tanlang::ParsableASTNode>)+0x2a)
0x7fa6c4f5f7ed: (tanlang::Compiler::parse()+0x197)
0x7fa6c4f4d6da: (compile_files(std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, TanCompilation*)+0x47a)
0x7fa6c4f3006e: (cli_main(int, char**)+0x1335)
0x7fa6c4f438bd: (main+0x24)
0x7fa6bfdd70b3: (__libc_start_main+0xf3)
0x7fa6c4f2e04e: (_start+0x2e)

Process finished with exit code 134

Make ASTType immutable once created, like llvm::Type

... and use TypeNode to represent a type during parsing, which will be replaced into an ASTType during analysis phase

Error handling in Lexer

tan/src/lexer/lexer.cpp

Lines 266 to 271 in b2cb68f

 // TODO error handling 

 } 

 _token_infos.emplace_back(t); 

 } else if (line[current] == '"') { // string literals 

 auto *t = 

 advance_for_string_literal(line, current, line_len);

This issue was generated by todo based on a `TODO` comment in `b2cb68f` when #2 was merged. cc @tjysdsg.

'.' can only be followed by digits

tan/src/lexer/lexer.cpp

Lines 117 to 122 in 12ad011

 // TODO: '.' can only be followed by digits 

 is_float = true; 

 } else if (IS_DELIMITER(ch)) { 

 break; 

 } else { 

 report_code_error((*reader)[static_cast<size_t>(forward.r)].code, static_cast<size_t>(forward.r),

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

Recognize cpp source files and compile them seamlessly using tanc

The following command should work like tanc is compiling .cpp and .tan files at the same time, and then tanc should link them with no problems.

tanc main.tan thrid_party_code.cpp -I. -lruntime.so --exe -o a.out

tanc should recognize .cpp files first, compile them using clang, then compile .tan files, and finally link all object files

Test type_system.tan fails

DO NOT exit the program when errors occurred

tan/src/lexer/lexer.cpp

Lines 236 to 241 in 12ad011

 // TODO: DO NOT exit the program when errors occurred 

 std::vector<token *> tokens; 

 const auto end = reader->back_ptr(); 

 while (start < end) { 

 // if start with a letter 

 if (std::isalpha((*reader)[start])) {

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

support unicode

tan/include/reader.h

Lines 66 to 71 in 12ad011

 // TODO: support unicode 

 class Reader final { 

 public: 

 Reader() = default; 

 ~Reader();

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

optimise Reader for speed

tan/src/reader/reader.cpp

Lines 17 to 22 in 12ad011

 // TODO: optimise Reader for speed 

 void Reader::open(const std::string &filename) { 

 // TODO: check file attributes before reading 

 _filename = filename; 

 std::ifstream ifs(filename); 

 // read the whole file at once

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

support escape sequences inside char literals

tan/src/lexer/lexer.cpp

Lines 135 to 140 in 12ad011

 // TODO: support escape sequences inside char literals 

 // TODO: check line breaks inside two quotation marks 

 token *tokenize_char(Reader *reader, code_ptr &start) { 

 token *t = nullptr; 

 auto forward = reader->forward_ptr(start); 

 const auto end = reader->back_ptr();

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

Fix 'Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.' issue in compile-and-test.sh

CodeFactor found an issue: Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.

It's currently on:
compile-and-test.sh:5
Commit 78fa6f3

New syntax for pointer dereference

Currently, pointer dereference is written as:

ptr.*

But it's not consistent with the syntax of this language. More specifically, there's not a clear way to define the token type of * in this situation. It's definitely not a unary operator, and we probably shouldn't treat .* as a whole because . itself is a member access operator.

This syntax was originally inspired by zig. But now I start to think that this is against the syntax consistency goal of this language.

	// TODO: check line breaks inside two quotation marks
	token tokenize_char(Reader reader, code_ptr &start) {
	token *t = nullptr;
	auto forward = reader->forward_ptr(start);
	const auto end = reader->back_ptr();
	forward = skip_until(reader, forward, '\'');

	// TODO: support escape sequences inside string literals
	// TODO: check line breaks inside two quotation marks
	token tokenize_string(Reader reader, code_ptr &start) {
	token *t = nullptr;
	auto forward = reader->forward_ptr(start);
	forward = skip_until(reader, forward, '"');

	// TODO: check file attributes before reading
	_filename = filename;
	std::ifstream ifs(filename);
	// read the whole file at once
	std::string content((std::istreambuf_iterator<char>(ifs)), (std::istreambuf_iterator<char>()));
	// count the number of lines

	// TODO error handling
	}
	_token_infos.emplace_back(t);
	} else if (line[current] == '"') { // string literals
	auto *t =
	advance_for_string_literal(line, current, line_len);

	// TODO: '.' can only be followed by digits
	is_float = true;
	} else if (IS_DELIMITER(ch)) {
	break;
	} else {
	report_code_error((*reader)[static_cast<size_t>(forward.r)].code, static_cast<size_t>(forward.r),

	// TODO: DO NOT exit the program when errors occurred
	std::vector<token *> tokens;
	const auto end = reader->back_ptr();
	while (start < end) {
	// if start with a letter
	if (std::isalpha((*reader)[start])) {

	// TODO: support unicode
	class Reader final {
	public:
	Reader() = default;

	~Reader();

	// TODO: optimise Reader for speed
	void Reader::open(const std::string &filename) {
	// TODO: check file attributes before reading
	_filename = filename;
	std::ifstream ifs(filename);
	// read the whole file at once

tjysdsg / tan Goto Github PK

tan's Introduction

Jiyang (Mark) Tang

tan's People

Contributors

Stargazers

Watchers

Forkers

tan's Issues

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in b2cb68f when #2 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a TODO comment in 12ad011 when #6 was merged. cc @tjysdsg.

Recommend Projects

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This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `b2cb68f` when #2 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.

This issue was generated by todo based on a `TODO` comment in `12ad011` when #6 was merged. cc @tjysdsg.